With the proliferation of the digital crime around the world, there are numerous and diverse digital forensic investigation models for driving digital investigation processes. Now more than ever, it must be a criminal investigation to obtain digital evidence which wouldn't be admissible in court. Therefore, digital forensic investigation should be implemented successfully, and there are a number of significant steps that should be taken into account. Each step and phase produces documents that are essential in understanding how the investigation process is built.The aim of this paper is to study models/ frameworks for the digital forensic investigation over a time period of ten years and find out the degree and level of attention to the process of documentation. This paper also includes definitions and descriptions of the basic and core concepts that the frameworks/ models use.

Digital forensic is part of forensic science that implicitly covers crime related to computer and other digital devices. It‟s being for a while that academic studies are interested in digital forensics. The researchers aim to find out a discipline based on scientific structures that defines a model reflecting their observations. This paper suggests a model to improve the whole investigation process and obtaining an accurate and complete evidence and adopts securing the digital evidence by cryptography algorithms presenting a reliable evidence in a court of law. This paper presents the main and basic concepts of the frameworks and models used in digital forensics investigation.

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Particular and timely unified information along with quick and effective query response times is the basic fundamental requirement for the success of any collection of independent data marts (data warehouse) which forms Fact Constellation Schema or Galaxy Schema. Because of the materialized view storage area, the materialization of all views is practically impossible thus suitable materialized views (MVs) picking is one of the intelligent decisions in designing a Fact Constellation Schema to get optimal efficiency. This study presents a framework for picking best-materialized view using Quantum Particle Swarm Optimization (QPSO) algorithm where it is one of the stochastic algorithm in order to achieve the effective combination of good query response time, low query handling cost and low view maintenance cost. The results reveals that the proposed method for picking best-materialized view using QPSO algorithm is better than other techniques via computing the ratio of query response time and compare it to the response time of the same queries on the materialized views. Ratio of implementing the query on the base table takes five times more time than the query implementation on the materialized views. Where the response time of queries through MVs access were found 0.084 seconds while by direct access queries were found 0.422 seconds. This outlines that the performance of query through materialized views access is 402.38% better than those directly access via data warehouse-logical.

Chain of custody plays an important role in determine integrity of digital evidence, because the chain of custody works on a proof that evidence has not been altered or changed through all phases, and must include documentation on how evidence is gathered, transported, analyzed and presented. The aims of this work is first to find out how the chain of custody has been applied to a wide range of models of the digital forensic investigation process for more than ten years. Second, a review of the methods on digitally signing an evidence that achieves the successful implementation of chain of custody through answering a few questions "who, when, where, why, what and how", and thus providing digital evidence to be accepted by the court. Based on the defined aims an experimental environment is being setup to outline practically an acceptable method in chain of custody procedure. Therefore, we have adopted SHA512 for hashing and regarding encryption RSA and GnuGP is applied where according to the defined requirement a combination of this algorithms could be adopted as a practical method.